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Validate buffer length before reading fields in Packet::readFrom #1666

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Validate buffer length before reading fields in Packet::readFrom #1666

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d10fcd4
Validate buffer length before reading fields in Packet::readFrom
weebl2000 Feb 11, 2026
ef97fe2
Clarify bounds check comment in Packet::readFrom
weebl2000 Feb 11, 2026
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4 changes: 3 additions & 1 deletion src/Packet.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -39,18 +39,20 @@ uint8_t Packet::writeTo(uint8_t dest[]) const {
}

bool Packet::readFrom(const uint8_t src[], uint8_t len) {
if (len < 2) return false; // minimum: header + path_len
uint8_t i = 0;
header = src[i++];
if (hasTransportCodes()) {
if (i + 4 >= len) return false; // need 4 transport bytes + the path_len byte
memcpy(&transport_codes[0], &src[i], 2); i += 2;
memcpy(&transport_codes[1], &src[i], 2); i += 2;
} else {
transport_codes[0] = transport_codes[1] = 0;
}
path_len = src[i++];
if (path_len > sizeof(path)) return false; // bad encoding
if (i + path_len >= len) return false; // path + at least 1 byte payload must fit
memcpy(path, &src[i], path_len); i += path_len;
if (i >= len) return false; // bad encoding
payload_len = len - i;
if (payload_len > sizeof(payload)) return false; // bad encoding
memcpy(payload, &src[i], payload_len); //i += payload_len;
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